ESP8266 NodeMCU Backdoor uPWM hack for IR signals

ESP8266-NodeMCU-uPWM-Inverted-IR-Circuit

The AnalysIR crew has published an article showing how to achieve accurate PWM for Infrared carrier signals on the ESP8266 NodeMCU:

Quite simple really – just set the baud rate to 10 times the desired Infrared carrier frequency and send a ‘magic’ 8 bit character to achieve the desired duty cycle. Of course we need to take the 1-start bit and 1-stop bit into account plus the 8 bits in each character. Remember that the UART sends the data inverted, so this needs to be taken into account with the characters sent and also in the IR LED driver circuit above, which required 2 transistors instead of the usual one.

More details at AnalysIR blog.

215 Hopper FPV rebuild

215HopperFPV

Andrew Taylor documented his 215 Hopper FPV build:

I finally have the design of the 215 Hopper at a point where I think it is fit for purpose as an FPV copter. It can now sustain a heavy grounding without terminal damage. I still won’t claim that it is as durable as a carbon plate design but I am now happy to release it. The camera pod is perhaps the least durable part of the design however I am still flying with the first one I printed and it has served its purpose protecting the flight cam. I do intend to upgrade it at some point but that will probably come after the custom camera pod for my Shendrones Tweaker.

All project files are available at Thingiverse.

More info at Andrew Taylor’s blog.

Understanding Arduino UNO hardware design

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Yahya Tawil over at All About Circuits has published an article on Arduino UNO’s electronic design and better understanding of its hardware:

This article explains how Arduino works from an electronic design perspective.
Most articles explain the software of Arduinos. However, understanding hardware design helps you to make the next step in the Arduino journey. A good grasp of the electronic design of your Arduino hardware will help you learn how to embed an Arduino in the design of a final product, including what to keep and what to omit from your original design.

Full details at All About Circuits homepage.

#FreePCB via Twitter to 2 random RTs

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Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters. Don’t forget there’s free PCBs three times a every week:

  • Hate Twitter and Facebook? Free PCB Sunday is the classic PCB giveaway. Catch it every Sunday, right here on the blog
  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs will be your friend for the weekend

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Check out how we mail PCBs worldwide video.
  • We’ll contact you via Twitter with a coupon code for the PCB drawer.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.

Georges F6DFZ’s very stylish homebrew version of the Scout Regen receiver

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Dave Richards AA7EE has published an article about Georges F6DFZ’s homebrew regen receiver:

Several months ago, Georges F6DFZ sent me pictures of a Manhattan project he had just completed, using Rex’s MeSQUARES, and I have waited far too long to share it with you. It began life as a copy of the Ten Tec 1253 regen, but George said that the results and usability were very poor. One thing that must be said about regens is that the ones which don’t work well are very dispiriting. However, when you come across a good design and build it well, the performance can be very satisfying indeed. Luckily, Georges didn’t let his initial regen experience put him off, and he ended up turning the project into a receiver based on the Kitchin-inspired Scout Regen. He normally uses PCB software to design custom boards for his projects, but decided to try Manhattan construction for this receiver.
I like how his project was obviously the result of considerable careful planning

More details at Dave Richards AA7EE blog.

HydroBot

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Matthew Reed writes:

HydroBot is a modular control system for automating hydroponic gardens. This system is designed with three objectives in mind. First, it will facilitate optimal growing techniques by using scheduling and feedback control loops to maintain state and adapt to changing conditions. Second, it will simplify controls interfaces, making setup and use easier for less tech-savvy gardeners. Finally, the components will be designed in a modular way to increase flexibility and support every imaginable garden configuration. HydroBot aims to bring sensors and actuators together through automation, which will allow hobby growers to focus on growing and not on constantly monitoring and adjusting the environment to keep their garden stable.

More details at Protofusion.org.

App note: Limiting inrush current

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Aimtec’s app note on inrush current on power converters and their solution. Link here

Inrush currents can be problematic in circuits that utilize overload protection devices such as fuses and circuit breakers. The selection of overcurrent protection devices is made more complicated when high inrush currents are present. False overload conditions can trigger unwanted protection events.

Free PCB Sunday: Pick your PCB

IRToy We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service. This week two random commenters will get a coupon code for the free PCB drawer tomorrow morning. Pick your own PCB. You get unlimited free PCBs now – finish one and we’ll send you another! Don’t forget there’s free PCBs three times every week:

Continue reading “Free PCB Sunday: Pick your PCB”

App note: Forced air convection and heat sinking for power supplies

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Application note from Aimtec discusses about two ways for taking away heat on power supplies. Link here

When evaluating the operating temperature ranges of power supplies one must consult component’s datasheets. Datasheets state a “usable” operating temperature range typically given at full output load. In order to reach the upper limit of the temperature ranges without derating the load, some additional heat dissipation may be required.

App note: System design guidelines for the TM4C129x family of Tiva C series microcontrollers

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System design guidelines from Texas Instruments for the TM4C129x Tiva C series microcontrollers, app note here (PDF!):

The Tiva™ C series TM4C129x microcontrollers are highly-integrated system-on-chip (SOC) devices with extensive interface and processing capabilities. Consequently, there are many factors to consider when creating a schematic and designing a circuit board. By following the recommendations in this design guide, you will increase your confidence that the board will work successfully the first time it is powered it up.

Reaction tester

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Reaction tester project from Vagrearg:

The single gate-type NAND version was put onto a PCB and tested. It works like a charm. There were only 74AC00 chips available at the time, but they are just about the same as HC chips. You can get the design files, which are made with KiCad. The layout is kept as symmetrical as possible and the A/B buttons are next to the LEDs. Power is supplied using three AA batteries in a standard battery-holder and the PCB is stuck onto the battery-holder with double-sided sticky tape.

Full details at Vagrearg project page.

Pi Zero POV

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Francesco over at Garage Tech posted a detailed how-to on building a Raspberry Pi Zero POV setup to display text from a file using an LED:

The most important part of getting the Pi Zero POV to run smoothly is given by how do you fix the payload of this spinning rocket onto the CD. Placing the Pi Zero in the right place will make so that when turning, the whole setup will have as little as possible vibrations. The rule of thumb we followed was to drill two 3 mm holes on opposite sides of the central hole of the CD and so that they would sit on one of the disk diameters.

Full details at Garage Tech homepage.

DIY smart glasses

DIY-Smart-Glasses

Harris has been working on his DIY smart glasses:

The glasses themselves are based around an STM32F051K8 microcontroller (LQFP32 for easy soldering!). All the firmware is custom written though I got the LCD driver initialization codes from the BuyDisplay examples. The firmware is written using a somewhat “co-operative scheduling” with interrupts methodology and for most of the time, the microcontroller is sleeping until something needs to happen. Along side all the Bluetooth and LCD software, I’ve included my SoftTouch library for the two touch buttons on the side of my glasses. These are used to change screens and change items within the screen e.g. move to the next news entry.

Project info at Harris’ Electronics site.

Via Hacked Gadgets.

ATtiny based bidirectional motor control using L293D

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Rahul over at Xanthium has posted a tutorial on interfacing ATtiny with L293D:

In this tutorial we will learn to interface L293D with ATMEL ATtiny microcontroller and control them bidirectionally.The microcontroller used here is ATtiny2313A which is interfaced to two L293D motor control chips for controlling upto 4 DC brushed motors.You can control upto 8 motors if bidirectional control is not needed.
The ability to control upto 4 motors is essential when we are building 4 wheel drive robotic projects like Rovers or under water ROV’s.

More details at Xanthium homepage.

Programmable relay switch using PIC MCU (revised version)

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Raj has documented his DIY programmable relay switch using PIC16F1847 microcontroller:

Here are the summary of the features that this programmable relay switch has:

  • On-board +5V voltage regulator (operates at 9-15V DC input)
  • OFF and ON time setup for the relay operation
  • Option for cyclic run (maximum 100 cycles, after which the timer stops automatically)
  • Stores ON/OFF times and Cyclic option from previous setup into internal EEPROM
  • ON/OFF timing range: 0 to 99 hours and 59 minutes with 1 min resolution
  • Interactive user interface using 4 tact switches and a character LCD
  • On-board buzzer alarm

More details at Embedded Lab site.

Check out the video after the break. Continue reading “Programmable relay switch using PIC MCU (revised version)”

SNAFU box

SNAFU Box

A SNAFU box project by Bertho of Vagrearg:

SNAFU Box consists of 24 LED strips (12V passive type) of varying size, which are controlled by a set of 74HC595 shift-registers and a transistor driver for each strip and RGB channel. The LED strips are used to backlight the lettering of the box. An additional three 74HC595 shift-registers are used for 4×4 matrices of blue LEDs, which are used to count the number of times a particular expression has been activated. Everything is controlled by an Arduino Pro Mini (5V) and an RTC (DS1307) keeps time and stores the current state (so it can be restored on power-failure).
The schematics are straight forward. The 4×4 matrix is divided into two PCBs. One for the electronics and one for the LEDs. The LED driver board and the 4×4 matrix boards use three identical copies for the entire design. The control board is created with KiCad, while the other PCBs are created with gEDA. The control board was created later, rather ad hoc, to replace a perfboard.

Project info at Vagrearg.org.

Wavetek 395 arbitrary waveform generator teardown

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Kerry Wong did a teardown of the Waveform 395 12 bit arbitrary waveform generator:

I picked up a Wavetek 395 arbitrary waveform generator on eBay a few weeks ago. Wavetek 395 is a single channel, 12-bit resolution DDS AWG with a maximum clock frequency of 100 MHz. While the operation manual is readily available, I could not find the service manual anywhere. So I was curious to see the construction inside. In this post, I will show you some of the teardown pictures. If you want to see a video of the teardown along with some analysis, you scroll towards the end of this post.

More info at Kerry D. Wong blog.

Check out the video after the break. Continue reading “Wavetek 395 arbitrary waveform generator teardown”

#FreePCB via Twitter to 2 random RTs

BP-600x373

Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters. Don’t forget there’s free PCBs three times a every week:

  • Hate Twitter and Facebook? Free PCB Sunday is the classic PCB giveaway. Catch it every Sunday, right here on the blog
  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs will be your friend for the weekend

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Check out how we mail PCBs worldwide video.
  • We’ll contact you via Twitter with a coupon code for the PCB drawer.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.